This invention relates to tools used for the drilling of oil and gas. The invention particularly relates to a well clean up tool and to its use.
It is considered desirable when drilling for oil or gas to maintain a clean interior in the casing or liner of the well. For this purpose, well cleaning apparatus is well known and comes in a variety of different forms. One such type of well cleaning apparatus is a casing scraper. This type of tool typically incorporates steel casing scraper blades that scrape the inside of the casing or tubing in the well. The steel blades provided with casing scrapers usually are designed to clean the casing interior of relatively large particles or debris, such as lumps of cement, rocks or congealed mud and so on.
A second type of well cleaning apparatus known in the art may be more accurately likened to a brush and incorporates cleaning pads with protruding bristles. Brushing tools are generally used to clean well casings, tubing and the like of smaller debris and or particles than that of scraper tools. Brushing tools may be used to remove oxidation lumps, scale, paraffin and burrs for example.
As the brushing tools offer a more finishing cleaning operation than the casing scrapers, it would be desirable to run a brushing tool after a scraper tool, but for the cost of running two tools. Often the time and associated coat of hiring and running two cleanup tools is prohibitive. Having to withdraw the scraper from the well, replace it in the drill string with a brushing tool and then run the cleanup operation again is frequently considered difficult to justify. Also, simultaneously running both a scraper tool and a brushing tool in the same string means that one or both of the tools can not properly access the desired areas to be cleaned, such as near to the liner top; the combined tools not being sufficiently compact.
An object of the present invention is to provide an improved well cleanup tool that combines at least two types of cleaning members. For example a tool in accordance with the present invention may have both scraping and brushing cleaning members.
A further object of the present invention is to provide a compact well clean up tool with multifunctional cleaning members.